Global wheat, corn yields seen suffering from El Nino: Study

Based on the area harvested worldwide in 2000, about 22% of wheat suffered a 'significant' negative impact from El Nino

Global corn, rice and wheat yields appear to suffer from the El Nino weather event, while soybeans may benefit, according to a study led by agricultural-weather researcher Toshichika Iizumi.

An analysis of wheat productivity found global yields for the world's most widely grown grain were on average 1.4 per cent lower than normal in El Nino years, according to the study published in the journal Nature Communications. Signs are for an El Nino event to start later this year, according to the World Meteorological Organization.

An El Nino occurs every two to seven years and is caused by warmer surface water in the Pacific Ocean, while its counterpart La Nina is associated with cooler years. An El Nino in 2006 saw a slump in Australia's wheat crop, contributing to a run-up in prices that pushed global food costs to a then record in 2008. The four studied crops all seem negatively affected by La Nina, the cooler phase of the climate phenomenon known as the El Nino Southern Oscillation.

"The overall impacts of ENSO on global yields are uncertain," the researchers led by Iizumi of Japan's National Institute for Agro-Environmental Sciences wrote. "Our findings highlight the importance of ENSO to global crop production."

Based on the area harvested worldwide in 2000, about 22 per cent of wheat suffered "significant" negative impacts from El Nino, including in south and east Australia, Mexico, parts of China and the northwest US, the study indicated. About 6 per cent of wheat benefited significantly, including in parts of Russia, Argentina and northern China, the researchers found. Global wheat yields were 4 per cent lower than normal in La Nina years, the researchers found.

Dry conditions

El Ninos tend to lead to dry conditions in parts of Australia and Southeast Asia as well as the northern half of South America. Australia's wheat harvest fell to 10.8 million tonnes (mt) in 2006-07 from 25.2 mt, US Department of Agriculture data show.

In El Nino years, global corn yields were on average 2.3 per cent lower than normal, while they were 0.3 per cent lower in the cooler La Nina phase. About 24 per cent of corn suffered "significant: negative impacts from El Nino, including in parts of the US and China as well as in Mexico and Spain, while 8 per cent benefited significantly, particularly in Brazil and the Black Sea region, the study showed.

Water temperatures in the tropical Pacific have risen to levels similar with the onset of El Nino, and about two-thirds of climate models indicate thresholds to declare the event may be reached from June to August, the WMO said last month.

Soybean Advantage

Soybeans seem to benefit from El Nino, with average global yields 3.5 per cent higher in the warm phase, while they were found to be one per cent lower in cooler La Nina years. El Nino means a significant positive impact for 36 per cent of the planted area, mostly in Brazil and the US, and a significant negative effect on 9 per cent, mainly in India and parts of China.

Rice yields on average were found to be 0.4 per cent lower than normal in El Nino years, and 1.3 per cent lower in La Nina years, according to the study. During El Ninos about 7 per cent of the world's rice area experiences significant negative impacts, particularly in southern China, the study showed.

Wheat was harvested from 216 million hectares worldwide in the 2012-13 season, followed by corn with 177.2 million hectares and rice with 158 million hectares, according to the USDA. Farmers harvested 109.2 million hectares of soybeans.